1. Field of the Invention
The present invention relates to a workpiece conveying robot that supports and transports workpieces such as thin substrates with a hand. In particular, the present invention relates to a conveying robot that includes a detection unit that detects information of the workpiece on the hand.
2. Description of Related Art
The workpiece conveying robot is employed, for example, for transporting glass substrates in an LCD panel manufacturing plant. Techniques related to such workpiece conveying robots can be found, for example, in JP-A-No. 2012-121680.
The workpiece conveying robot according to JP-A-No. 2012-121680 is configured as an articulated robot. More specifically, the workpiece conveying robot includes the following. (1) A lower arm and an upper arm connected to each other so as to relatively rotate about a horizontal axis, (2) an upper base connected to the upper arm so as to rotate about a horizontal axis and a vertical axis, (3) a left arm and a right arm connected to the upper base so as to rotate about a vertical axis, and (4) a left hand and a right hand respectively attached to the distal end portion of the left arm and the right arm. The mentioned configuration allows the left and right hands to move to a desired position maintaining a horizontal orientation, by selectively rotating the lower arm, the upper arm, the upper base, and the left and right arms.
The left and right hands each include a sensor that detects the workpiece on the hand. A detection signal from the sensor is transmitted through a wiring to a control unit that controls the movement of each functional part of the workpiece conveying robot. The wiring is routed along the lower arm, the upper arm, the upper base, and the left and right arms, with a slack so as not to disturb the rotational movement of those components.
Some of the existing workpiece conveying robots include a linear moving mechanism that causes the hand to move in a horizontal linear stroke passage. For example, JP-A-No. 2006-123135 discloses such a workpiece conveying robot. The workpiece conveying robot according to JP-A-No. 2006-123135 includes a moving member placed on a pair of linear rails supported by a guide member, and a belt drive mechanism that drives the moving member. The guide member is movable in a vertical direction, and also rotatable. The moving member includes a hand on which the workpiece is to be placed.
The foregoing workpiece conveying robot including the linear moving mechanism may also include a sensor that detects the workpiece on the hand and a wiring connecting between the sensor and a control unit. In the robot including the linear moving mechanism, however, the wiring is bent in various patterns to follow up the long-range linear movement of the hand. To guide or protect the wiring that has to be bent, the wiring may be inserted through a bendable, caterpillar-shaped cable cover member.
However, since the cable cover member is bent and deformed owing to the transporting operation of the workpiece, particles may be generated at a slide-contact portion of the cable cover member, and the slide-contact portion may be damaged. Further, the wiring inside the cable cover member may also be damaged or disconnected, by repeatedly being bent in various patterns. In addition, in the case where the hand is set to travel over a long stroke passage the cable cover member also has to be extended, and may resultantly interfere with the rotational movement of the workpiece conveying robot.